Core photoelectron spectroscopy of some acetylenic molecules

Carbon 1s binding energies have been measured for CH₃CCH, CH₃CCCH₃, CF₃CCH and CF₃CCCF₃ and compared to a verified value for acetylene. Assignments are based on the application of a CNDO potential model with relaxation corrections which is quite successful in predicting binding energy shifts and upon qualitative considerations. Substitution of CF₃ groups shifts the acetylenic C 1s binding energy from 291.2 (HCCH) to 292.2 in CF₃CCH and 292.7 eV in CF₃CCCF₃. The unequal substitutional shifts are probably due to a saturation of substituent effect expected in competitive situations. With reservations arising from uncertainties in assignment due to lack of resolution, it appears that acetylenic C 1s binding energies decrease [to 290.7 (av.) in CH₃CCH and to 290.1 eV in CH₃CCCH₃] upon replacement of H by CH₃ groups. Although the decrease in acetylenic binding energies agrees with the chemical notion that CH₃ groups are electron donating with respect to unsaturated portions of the molecule, theoretical calculations available in the literature indicate that actual electron withdrawal or donation does not occur in these differently substituted molecules. The shifts of apparent binding energy correlate reasonably well with a ground state potential model which accounts for the effect of the charge on the adjacent atoms as well as on the photoionized atom. Even better correlation is obtained if the atomic potentials are corrected for electronic redistribution (relaxation) effects which occur during the photoionization process, and it is suggested that relaxation effects make a significant contribution to shifts of apparent binding energies. Surprisingly ground state potential and relaxation corrected potential calculations with the CNDO method suggest a large difference in C 1s binding energies of the two acetylenic carbon atoms in CH₃CCH which is not verified experimentally nor mirrored by calculations on CF₃CCH. The CH₃ binding energies are 291.8 eV in CH₃CCH and 291.3 eV in CH₃CCCH₃, both higher than values assigned to CH₄ or C₂H₆.     

Grahamimycin A1: a novel dilactone antibiotic from cytospora

By means of spectral and chemical studies the structure of Grahamimycin A₁$\text{1}$, a novel macrocyclic dilactone antibiotic from Cytospora, is established.     

d + α Scattering from 12 to 17 MeV

A previous phase-shift analysis of the d + α system had indicated that the solution obtained might not describe the backward-angle tensor analyzing powers very well above about 10 MeV. We have measured differential cross sections and all four analyzing powers A_y, A_xx, A_yy and A_xz at deuteron bombarding energies of 12, 14, 15 and 17 MeV, with some emphasis on the backward-angle region. The discrepancy with the previous phase-shift analysis was confirmed, and we have studied the changes in the phase parameters necessary to improve the fit to our new measurements.     

The personalization of security selection: An application of fuzzy set theory

We apply the theory of fuzzy subsets to the multiple objective decision problem of stock selection. We allow our objectives to have varying degrees of importance. We discuss various criteria used in selecting stocks. We indicate some procedures for subjectively evaluating the membership functions associated with these criteria.     

Solubility of solid mixtures in supercritical fluids

Kurnik, R.T. and Reid, R.C., 1982. Solubility of solid mixtures in supercritical fluids. Fluid Phase Equilibria, 8: 93-105Supercritical fluids are receiving widespread attention as possible extraction agents for relatively non-volatile solids and liquids. Previous studies of the solubility of solids in supercritical fluids have been limited to pure solids. These pure-component data are interesting and indicate novel properties of supercritical fluids in this respect. The more general problem, however, lies in determining the solubility of multicomponent solids in supercritical fluids. Experimental data have now been obtained on the solubilities of binary, solid hydrocarbon mixtures in both supercritical carbon dioxide and supercritical ethylene. Most of the behavior exhibited by pure solids in supercritical fluids still exists for multicomponent solid solute systems (e.g., retrograde solidification, solubility extrema), but new phenomena were also found. The most interesting finding is that the solubility of a solid component when in a multicomponent solute system can be as much as 300% higher than the component solubility in a pure solid system at the same operating conditions. The multicomponent-solid-fluid data usually correlate well with thermodynamic theory.     

Carbon-13 substituent chemical shifts of 4-substituted bicyclo[2.2.2]oct-1-yl cyanides

The carbon-13 substituent chemical shifts of 4-substituted bicyclo[2.2.2]oct-1-yl cyanides are a linear function of the substituent inductive parameters.